Electrostatographic printing machines have been developed which use one or more replaceable sub-assemblies called customer replaceable units (CRU). One typical CRU contains the photoreceptor and the necessary supporting hardware therefor assembled in a single unit designed for insertion and removal into and out of the machine by the user. When the CRU is no longer operational, the old CRU is removed and a new one installed.
For small cylindrical photoreceptors in correspondingly small CRUs, drive gears are relatively expensive, necessitating shafts, bearing surfaces, and flanges to attach to the photoreceptor, as well as inherently mechanically noisy due to the discrete nature of momentum transfer in a toothed gear system. In addition, ensuring surface motion tracking between the image-writing laser beam and the transfer point of toner to paper to ensure faithful digital image reproduction in a monochrome printer or color fidelity in a tandem color printing machine in which the surface motion tracking additionally must follow from photoreceptor to photoreceptor as well as within the photoreceptor, relies on both uniform rotation rate and controlled photoreceptor radji to minimize error in a gear driven system. The present invention achieves the necessary motion quality while using reduced cost parts and relaxing the radial uniformity requirements for the photoreceptor.
Conventional consumer replaceable units are disclosed in Imes, U.S. Pat. No. 5,537,189; Ebata et al., U.S. Pat. No. 4,975,744; Harlan, U.S. Pat. No. 5,307,117; and Everdyke et al., U.S. Pat. No 5,243,384, the disclosures of which are totally incorporated herein by reference. In addition, Michlin, U.S. Pat. No. 5,402,207, discloses a long-life and improved photoreceptor drum gear.